Exam 3: Endocrine and Reproductive Systems

Question 1

What is the endocrine system responsible for?

Answer 1

communication and coordination (along with NS)
uses chemical signals called hormones
includes multiple organs spread throughout the body

Question 2

Nervous system vs. endocrine system

Answer 2

both participate in communication
but differ in their speed and means or signaling

Nervous system:
uses both electrical and chemical signaling, electrical: direct action of electrical potential, chemical: neurotransmitters, very rapid response (milliseconds)

Endocrine system”
uses chemical signaling only, chemical: hormones transported in blood stream, slower response (seconds to days), less specific (may have different effects in different cells)

Both systems are connected: fight or flight response

Question 3

What are the major organs of the endocrine system?

Answer 3

pituitary gland, adrenal gland, thyroid gland, parathyroid gland, pancreas, pineal gland, thymus, gonads

Question 4

What are the secondary organs of the endocrine system?

Answer 4

skin, heart, GI tract, kidneys, liver, placenta, adipose tissue

Question 5

exocrine vs. endocrine glands:

Answer 5

Exocrine: release secretions through ducts, ex: sebaceous and sweat glands of skin, liver (bile), pancreas (digestive juices)

Endocrine: ductless, secrete hormones into surrounding fluid
dense capillary networks or lymphatics pick up hormones and transport them

Question 6

What are the other local chemical messengers?

Answer 6

Hormones: diffuse into blood or lymph and travel throughout the body

Autocrines: chemicals that elicits response in the same cell that secreted it

Paracrines: induces a response in neighboring cells

Question 7

What are the two major groups hormones can be divided into?

Answer 7

hormones derived from amino acids
includes amines, peptides, and proteins

hormones derived from lipids
includes steroids

affects hormone distribution and type of receptor is binds to

Question 8

Explain amine hormones:

Answer 8

synthesized form amino acids tryptophan or tyrosine (amino acid structure modified)

Question 9

Explain peptide and protein hormones:

Answer 9

differ in amino acid chain
peptide: short chain
amino acid: long chain
synethsized like other body proteins DNA->mRNA->amino acid chain
Peptide: ADH
Protein: growth hormone

Question 10

Explain steroid hormones:

Answer 10

derived from lipid cholesterol
not soluble in water
must travel bound to transport protein, extends half life of the hormone
ex. testosterone and estrogen

Question 11

Explain the action of hormones:

Answer 11

hormones bind to a hormone receptor -> protein located inside the cell or within the cell membrane, receptors are specific (recognize hormones with specific shapes and side groups)

Binding of hormone to receptor initates a response
same type of receptor in different tissue may trigger different response (ex. epinephrine)

Question 12

what are the responses of hormones?

Answer 12

stimulation of protein synthesis
activation/deactivation of enzymes
changes to cell membrane permeability
altered rates of mitosis and cell growth
stimulation of product secretion

Question 13

What is an intracellular hormone receptor?

Answer 13

receptors located inside the cell
hormones must be able to cross cell membrane
steroid hormones can diffuse through bilayer, thyroid hormones have carrier proteins

binding to receptor creates hormone-receptor complex -> binds to DNA -> triggers transcription of target gene to mRNA, followed by protein synthesis

Question 14

What is a cell membrane hormone receptor?

Answer 14

receptors located on cell surface
amino acid derived hormones cannot diffuse through bilayer (exception: thyroid hormones)

binding to receptor initates signaling cascade, carried out by secondary messenger, usually cAMP

Question 15

What is a phosphorylation case in cell membrane hormone receptors?

Answer 15

phosphorylation of proteins can trigger a variety of effects:
changes to nutrient metabolism
synthesis of different hormones and other products

increases efficiency, speed, and specificity or hormonal response
1000s of signaling events can be triggers simultaneously, can respond to low concentrations of hormone in blood stream

signal duration is short -> cAMP is deactivated by enzyme PDE

Question 16

What is a target cell?

Answer 16

for a target cells to respond to a hormone, it must have specific receptors that the hormone can bind to

target cell activation depends on: blood levels of the hormone, number of receptors for that hormone on or in target cell, affinity if binding between hormone and receptor

Question 17

What is a large vs reduced hormonal effect?

Answer 17

large: higher hormone levels, more receptors, higher affinity

reduced: lower hormone levels, fewer receptors, lower affinity

Question 18

How are hormone receptors regulated? up and down

Answer 18

up regulation: low levels of hormone increases the number of receptors for that hormone, cells become more sensitive to hormone

downregulation: high levels of hormone causes decrease in the number of receptors for that hormone, cells become less reactive to excessive hormone levels

Question 19

how can hormones interact?

Answer 19

two or more hormones can interact to affect response of cells

permissive effect: presence of one hormone allows a another to act

synergistic effect: two hormones with similar effects produce amplified response, two hormones may be required for the cells to respond at all

antagonistic effect: two hormones have opposing effects

Question 20

what system regulates hormones?

Answer 20

negative feedback systems, some are positive

Question 21

Manufacture and release of hormones can be triggered by:

Answer 21

humoral stimuli: changing blood levels of ions and nutrients triggers hormone secretion

neural stimuli: nerve fibers stimulate hormone release

hormonal stimuli: endocrine glands release hormones in response to hormones produced by other glands

Question 22

negative feedback vs. positive feedback:

Answer 22

negative: response is reverse of change detected

postive: response reinforces change detected

Question 23

what are the secondary endocrine organs?

Answer 23

heart
GI tract
kidneys
skeleton
adipose tissue
thymus
liver

Question 24

What is sexual reproduction?

Answer 24

combine genes from two parents
union of two gametes to form zygote (fertilized egg), male gametes: sperm, female gametes = egg
sexes typically defined by their sex chromosomes (male XY and female XX)

Question 25

What are the primary and secondary sex organs in males?

Answer 25

primary: produce gametes-> testes secondary: necessary for reproduction -> penis, ducts, glands

Question 26

What is spermatogenesis?

Answer 26

sequence of events that produce male gametes (sperm). starts at puberty, continues daily, ~120 million sperm made daily

Question 27

What is the site of spermatogenesis?

Answer 27

testes, sperm production occurs in the seminiferous tubules: surrounded by interstitial endocrine cells (leydig cels) -> secrete testosterone into interstitial fluid

Question 28

What are spermatogenia?

Answer 28

immature germ cells, 2-3 layers on inner surface of semiserious tubules, form from primordial germ cells that migrate into testes during embryonic development

Question 29

do spermatogenia undergo mitosis?

Answer 29

yes! type A daughter cells remain to maintain germ line type B daughter cells migrate towards lumen and are surrounded by nurse cells (Sertoli cells) -> become spermatocytes

Question 30

What are nurse cells?

Answer 30

aka supporting cells, Sertoli cells blood-testis barrier: connected by tight junctions of nurse cells, prevents immune system from attacking sperm antigens support sperm: regulate nutrients, hormones, environmental toxins that can enter tubules, waste removal

Question 31

Primary and secondary spermatocytes:

Answer 31

primary: undergo meiosis I -> produced 2 haploid cells called secondary spermatocytes -> undergo meiosis II -> produces 4 spermatids with 23 chromosomes in each

Question 32

What is a spermatid?

Answer 32

not quite sperm cells, small ,round, large nucleus, non-motile

Question 33

What is spermiogenesis?

Answer 33

spermatids elongate, shed cytoplasm, form tail now a sperm! head with flattened nucleus -> genetic storage, acrosome tail (flagellum) -> locomotor apparatus, mid piece (mitochondria = ATP)

Question 34

How are sperm stored?

Answer 34

sperm are stored in epididymis and vas deferent (may remain for month, kept inhibited)

Question 35

How do sperm move?

Answer 35

using flagella 1-4mm/min, movement enhances in neutral-slightly alkaline conditions (semen), increase in temperature will decrease activity, live 1-2 days after ejaculation

Question 36

Explain abnormal spermatogenesis: What do the darts and cremaster muscles do?

Answer 36

increase in temperature will decrease spermatogenesis scrotum maintains testes at lower than body temp necessary for sperm production Dartos: smooth muscle that wrinkles skin-> pulls closer to body Cremaster: skeletal muscles that elevates testes -> pulls closer to body

Question 37

What does the pampiniform plexus do?

Answer 37

absorbs arterial heat countercurrent heat exchanger -> blood entering the testes is cooled by blood leaving the testes

Question 38

What hormones are present in the male reproductive system?

Answer 38

GnRH, FSH, LH and testosterone

Question 39

What is the HPG axis?

Answer 39

FSH stimulates cells to release androgen-binding protein which keeps high [testosterone] near spermatogenic cells inhibition: testosterone feeds back to hypothalamus to inhibit GnRh, when sperm count is high, inhibit is released -> inhibits release of GnRH and FSH

Question 40

What is testosterone?

Answer 40

secreted by Leydig cells in testes ~20% of the mass of testes, increase in number after puberty

Question 41

What does testosterone do before brith, during puberty and as an adult?

Answer 41

Before brith: masculinizes reproductive tract and external genitalia Puberty: spermatogenesis, initials growth and development of male reproductive organs, secondary sex characteristics, sex drive, bond growth Adult: maintain functions initiated in puberty

Question 42

What are the two phases of the male sexual response?

Answer 42

erection and ejaculation

Question 43

What is the internal penis?

Answer 43

3 erectile bodies surrounded by dense fibrous connective tissue sheaths connective tissue and smooth muscle with many bloody sinuses 1 corpus spongiosum surrounds spongy urethra 2 pairs corpora cavernosa

Question 44

What is an erection?

Answer 44

erectile tissue fills with blood when not aroused: arterioles supplying erectile tissue are not constricted during sexual excitement, PNS releases NO NO activates enzymes that form cGMP which causes vasodilation of penile arteries-> expansion of erectile tissue compresses drainage veins

Question 45

What is erectile dysfunction?

Answer 45

inability to attain an erection, due to deficient release of NO can be caused by: psychological factors, alcohol, antidepressants and other drugs, chronic conditions may be treated with drugs like viagra which will blood PDE5-> and enzyme that breaks down cGMP cGMP regulates blood flow to penis -> more cGMP = more blood flow

Question 46

What is the male duct system?

Answer 46

sperm are made in the testes but must edit the body in semen for reproduction to occur, has accessory ducts

Question 47

What are the 4 accessory ducts:

Answer 47

Epididymis: coiled ducts that contract to expel sperm, sperm storage, maturation (20 days) and norushiment Ductus Vas Deferens: muscular duct travels through spermatic cord, joins with the.... Ejaculatory duct: travels through prostate and empties into the.... urethra: secreted lubriatcting mucus, shared between sperm and urine

Question 48

What are the accessory glands? seminal vesicles prostate Bulbo-urethral glands

Answer 48

seminal vesicles (2): contract during ejaculation yellowish viscous alkaline fluid (70% of semen), fructose for ATP production, enhances sperm motility and fertilizing capability, joins with dutus deferent to form ejactulatory duct Prostate: encircles urethra, milk, slightly acidic fluid (30% of semen) Bulbo (2): secretes before ejaculation, thick, clear mucus (not part of semen), lubriactes spongy urethra and glans penis, neutralizes traces of urine

Question 49

What is semen?

Answer 49

milky, white alkaline fluid ph: 7.2-8.0 sperm/acessory gland secretions function: transport medium for sperm ~2-5 mL/ejaculation with 100+ million spermW

Question 50

What is ejaculation?

Answer 50

occurs when sexual stimulus becomes intense SNS impulses exit spinal cord -> emission: vas deferens contract (pushes sperm into internal urethra), prostate gland and seminal vesicles contract (expel prostatic and seminal fluid, mixes with sperm) filling of internal urethra sends signals to spinal cord -> leads to rhythmic contractions or muscles that compress that base of the erectile tissues -> wave like contractions forces semen from the urethra -> propelled at 11 mph

Question 51

What is the refractory period?

Answer 51

occurs after ejaculation, the time during which it is impossible for a man to have additional orgasams, may be causes by oxytocin released during orgasam, increases with age

Question 52

oogenesis vs spermqtaigenis table

Answer 52

review table + meiosis differences

Question 53

What is oogenesis:

Answer 53

production of female gametes (occurs in ovaries, meiosis), takes years to complete (begins during fetal period and become active after puberty), cynical events (hormones, ovarian and uterine histological changes, uterine changes - menstrual flow, completed until menopause)

Question 54

What are the 2 areas of the ovaries?

Answer 54

cortex- forming gametes medulla- blood vessels and nervesW

Question 55

What are ovaries: follicles?

Answer 55

tiny sac like structures in the cortex, contain oocytes (immature eggs) follicles go through development and change in complexity if there is one layer of cells around the follicle : cells are follicle cells If more than one layer is present: granulosa cells

Question 56

Explain oogenesis in the fetus:

Answer 56

oogonia (2n) multiple via mitosis until month 5 (6-7 million) primary oocytes develop in primordial follicles (begins mitosis I before birth; stalls in prophase I, most degenerate by birth (1-2 million left) female infants have a lifetime supply of primary oocytes E

Question 57

Explain oogenesis after puberty:

Answer 57

~200,000 remain at puberty, 20-25 primary oocytes activated monthly (most degenerate, one is "selected" -> dominate follicle containing oocyte -> resumes meiosis I) primary oocyte in dominant follicle finishes meiosis I -> 2n daughter cakes secondary oocyte: large, has most of mother cell's cytoplasm and organelles first polar body: small, mostly devoid cytoplasm secondary oocyte stalls in metaphase II -> destined to be ovulated, if not penetrated by sperm -> deteriorates if penetrated, completed meiosis II zygote and second polar body

Question 58

What is down syndrome?

Answer 58

caused by an extra copy of chromosome 21 (trisomy 21), maternal age is an important factor is the frequent of trisomy

Question 59

What is the ovarian cycle?

Answer 59

monthly series of events that matures an egg, may happen ~500 times throughout life

Question 60

What are the phases of the ovarian cycle?

Answer 60

Follicular phase (days 1-14) - mature vesicular follicle grows ovulation occurs mid-cycle Luteal phase (days 14-28) - corps luteum activity

Question 61

What are the stages of the follicular phase?

Answer 61

1. primordial follicle rising levels of FSH stimulation activation of follicles, Midway through follicular phase, FSH drops -> one follice becomes dominant follice and continues to grow, remaining follicles disintegrate 2. Primary follicle 3. Secondary follicle 4. Tertiary follicle 5. Mature vesicular follicle

Question 62

What is ovulation?

Answer 62

ovary wall ruptures and expels the secondary oocyte, 1-2% of ovulations release >1 secondary oocyte

Question 63

What occurs in the luteal phase?

Answer 63

ruptured follicle collapses -> granulosa cells and internal theca cells from corpus luteum -> secretes progesterone and estrogen -> stimulates the thickening of the uterine wall If pregnancy occurs: corpus luteum produces hormones until the placenta takes over at about 3 months If no pregnancy, the corpus luteum degenerates into a corpus albicans in 10 days

Question 64

How is the ovarian cycle hormonal regulated?

Answer 64

hypothalamus releases GnRH -> anterior pituitary releases FSH and LH -> in the ovaries, follicles grow, mature, secrete estrogen -> low levels of estrogen being secreted by follicle inhibits FSH and LH Dominant follicle released constant level of estrogen -> anterior pituitary -> LH surge just before ovulation -> oocyte completes meiosis I -> ovulation1 -> ruptured follicle -> corpus luteum -> inhibits FSH/LH again

Question 65

How does the corpus luteum play a role in hormonal regulation of the ovarian cycle?

Answer 65

Corpus lutem-> progesteron, estrogeen, inhibin anterior pituitary and hypothalamus -> inhibits FSH and LH -> prevents other follicles from maturing -> prevents other oocytes from being ovulated uterus -> cervical mucus thickens -> preps endometrium for pregnancy

Question 66

What is the pathway of the secondary oocyte? simple

Answer 66

ovulated secondary oocyte exits ovary -> enters peritoneal cavity -> then....uterine tubes!

Question 67

What are the uterine tubes? + components

Answer 67

AKA fallopian tubes, secondary oocyte passed through to uterus isthmus: where UT empties into uterus ampulla: widened area infundibulum: funnel-shaped and ciliated fimbriae: finger-like projections sweep ovum in

Question 68

What is the pathway of the secondary oocyte continued?

Answer 68

enters uterine tube and progress to uterus (3-4 day journey) for fertilization to occur, secondary oocyte must be penetrated by sperm within 12-24 hours after ovulation (meiosis II occurs here, uterine tubes)

Question 69

What is the uterus?

Answer 69

thick, muscular walls (nourished embryo/fetus), size and shape of inverted pear

Question 70

What are the 3 layers of the uterine wall?

Answer 70

perimetrium (outer): serous membrane myometrium (middle): smooth muscle contracts to expel fetus endometrium (inner): mucosal lining, simple columnar epithelium over a thick lamina propria, where embryo implants, 2 layers: functional and basal

Question 71

What is the uterine cycle = menstrual cycle? purpose and interruptions

Answer 71

begins at puberty (~11-12 years old), cycle length = 21-35 days, continues until menopause, interruptions: pregnancy, illness, stress, starvation purpose: prepare uterus for possible embryo implantation

Question 72

What are the 4 phases associated with the endometrium?

Answer 72

menstrual phase (1-5): endometrial functional layer is shed proliferative phase (6-14): functional layer is regenerated secretory phase (15-26): thickening due to secretion and fluid accumulation rather than mitosis, cervical plug forms (keeps uterus private) premenstrual phase (27-28): AKA ischemic phase, brings on tissue necrosis changes directed by ovarian hormone levels of estrogen and progesterone

Question 73

explain the two layers of the endometrium and what they do:

Answer 73

Functional layer: cycles in response to hormones, shed during menstartion Basal layer: reforms functional layer after menstruation ends, proliferative phase of uterine cycle

Question 74

explain endometrial blood flow:

Answer 74

uterine artery -> arcuate arteries -> straight arteries -> spinal arteries Spinal arteries constrict and spasm causing shedding of functional layer degenerate and regenerate monthly, menstruation lasts 5-7 says (30-50mL of blood lost)

Question 75

High levels of ------- are responsible for the LH/FSH surge that promotes ovulation whereas low -------- inhibits LH/FSH

Answer 75

estrogen

Question 76

what is the vagina and its function?

Answer 76

thin walled distensible tube, 3-4 inches long, extends from cervix to exterior, acidic = reduces bacteria function: passageway; menstrual flow, copulation, delivery of infant

Question 77

What is the female sexual response?

Answer 77

similar to male PNS activity analogues to erectile phase in males Engorgment of: labia, clitoris, vaginal transudate, bulbs of vestibule, breasts, uterine tenting effect, vestibular glands secrete lubriacting mucus SNS implies discharge also analogous, but with no ejaculation. Muscular/uterine contractions associated with intense plessure

Question 78

What are the different ways to prevent pregnancy? 4

Answer 78

condoms/ vasectomy: prevent sperm from reaching vagina birth control pills: constant level of estrogen and progesterone inhibits release of FSH and LH -> prevents ovulation. Placebo pills cause a decline in hormones, triggering menses IUDs: may contain levonorgestrel -> inhibits release of FSH and LH -> prevents ovulation Plan B: contains levonorgestrel

Question 79

What is the journey of the sperm to the egg?

Answer 79

ejaculation releases hundreds of millions of sperm must overcome: vaginal acidity (pH 3.8), cervical mucus, uterine leukocytes only a few hundred thousand make it to the uterine tubes

Question 80

What is capacitation?

Answer 80

fluids in the female reproductive tract prepare sprem for fertilization, must undergo this process in order to penetrate egg improve motility thin membrane of the sperm head

Question 81

How does the sperm contact the oocyte?

Answer 81

corona radiata: granulosa cells form oocyte development, secrete chemical attractants for sperm sperm burrow through corona radiatia, bind to receptors in zone pellucida acrosomal reaction: enzymes released from the acrosome all sperm ti reach oocyte sperm contacts sperm-binding receptors on oocyte plasma membrane fuses with oocytes membrane

Question 82

How is polyspermy prevented?

Answer 82

only one sperm cell and fertilize an oocyte when sperm first binds to plasma membrane: fast block: change in sodium ion permeability -> prevents further sperm from fusing slow block: granules beneath plasma membrane release inhibiting proteins -> release other attached sperm, destroy sperm receptors, mucopolysaccharides create barrier called fertilization membrane

Question 83

What occurs prior to and after fertilization?

Answer 83

Prior: oocyte arrested in metaphase II, once fertilizes, meiosis is completed, genetic material intermingles, resulting in a diploid zygote mitosis causes growth of zygote at ~70-100 cells, called a blastocyst blastocyst adheres to uterine wall -> begins implantation

Question 84

What is implantation?

Answer 84

blastocyst embed in uterine lining (50-75% of blastocyst fail to implant) blastocyst digests uterine wall -> mucosa rebuilds itself, surrounding the blastocyst hCG is secreted -> directed corpus luteum to survive -> continues to produce progesterone and estrogen hCG is detectable in urine (at home pregnancy tests)

Question 85

How do endocrine organs play a role in pregnancy?

Answer 85

for the first 7-12 weeks, hormones are primarily secreted by the corpus luteum progesterone stimulates production of cells that nourish the blastocyst before the placenta during weeks 12-17, the placenta takes over -> corpus luteum degenerates, convertes hormones secreted by maternal and detal adrenal glands to estrogens-> estrogen levels increases 30X by childbirth

Question 86

What is the role of estrogens?

Answer 86

Suppress FSH and LH induce growth of fetal tissues maturation of fetal lungs and liver regulate progesterone production triggers fetal synthesis of cortisol (maturation of lungs, liver, and endocrine organs) stimulate maternal tissue growth (uterus and mammary glands)W

Question 87

What are the other hormones secreted by luteum and then the placenta?

Answer 87

Relaxin: increases elasticity of pubic symphysis and pelvic ligaments -> dilates cervix during labor Progesterone: supresses FSH and LH -> inhibits uterine contractions, levels drop in late gestation hCG: stimulates male detal gonads to secrete testosterone, essential for development of male reproductive system

Question 88

What are the other hormones secreted by the anterior pituitary in pregnancy? And the parathyroid?

Answer 88

Thyrotropin: increases production of thyroid hormone, increases maternal metabolic rate -> increases appetite and causes hot flashes Prolactin: enlargement of mammary glands ACTH: stimulates protein synthesis via cortisol Parathryoid: Parathyroid hormone: mobilizes free calcium for fetal use

Question 89

Which hormones are active in labor and what do they do?

Answer 89

progesterone levels plateau and then drop around month 7 increasing estrogen:progesterone ratio makes smooth muscle of uterus more sensitive at ~8 months, fetal cortisol rises -> further boost estrogen secretion Near labor, posterior pituitary secretes more oxytocin -> stimulates contractions and release of prostaglandins (also stimulates contractions), artificial version of these hormones can induce labor

Question 90

What is sex determination?

Answer 90

sex chromosomes X and Y. XX=female and XY=male , variations do exist Gametes from mother- always contain X chromosome Gametes from father- 50% X 50% Y, determines sex of offspring

Question 91

What is the Y chromosome?

Answer 91

single gene that initiates testes development SRY without SRY, embryos develop as females

Question 92

What is nondisjunction?

Answer 92

can lead to aneuploidy - more or less than 2 copies of each chromosome

Question 93

Typical development aneuploidy:

Answer 93

Genotype: XX or XY Phenotype: Female (XX) or male (XY)

Question 94

How does differentiation of the reproductive system occur?

Answer 94

male and female embryos being with the same structures, sexually indifferent stage, contain bipotenital tissues

Question 95

What are biopotential tissues?

Answer 95

cells that develop into either male or female gonads testosterone can influence biopotential tissues t0 become male reproductive structures

Question 96

What are non-biopotential tissues? Two duct systems

Answer 96

internal reproductive structures: uterus/ uterine tubes/ portions of vagina, epididymis/ ductus deferens/seminal vesicles form from one of two duct systems: female ducts: Mullerian duct Male ducts: Wolffian duct

Question 97

What is the gonadal ridge?

Answer 97

begin development during week 5 primordial germ cells migrate here, will become spermatogonia or oogonia gonadal ridges then form tests or ovaries

Question 98

Explain male internal developement:

Answer 98

SRY gene creates testes determining factor (TDF) -> gonadal ridge develops into testes testes produce: MIF -> causes degeneration of Müllerian duct testosterone: promotes development of male sex characteristics

Question 99

Explain female internal development:

Answer 99

No SRY gene -> absence of TDF Gonadal ridge develops into ovaries ovaries do not produce MIF or testosterone No MIF-> mullerian duct develops no testosterone: wolffian duct degenerates

Question 100

What does external genitalia arise from?

Answer 100

genital tubercle, depends on presence or absence of testosterone

Question 101

What is puberty?

Answer 101

individuals become sexually mature, results from development of secondary sex characteristics

Question 102

Explain the hormonal control of puberty: age 8-9 approaching onset

Answer 102

hypothalamus secretes GnRH, anterior pituitary secretes LH and FSH, gonads secrete testosterone or estrogen age 8-9: LH productions become detectable, negative feedback system is very sensitive low concentrations of androgens or estrogens inhibits hypothalamus and pituitary. GnRH, LH, and FSH production low Approaching: sensitivity of negative feedback decreases. gonads increase in sensitivity to FSH and LH, as a result, levels of LH and FSH increase and lead to maturation of gonads -> leads to secretion of higher levels of sex hormones Onset: may be influenced by nutrition, may be a link between puberty onset and amount of stored fat more pronounced in girls, may reflect metabolic costs of gestation and lactation, in lean ,active women, there's often a delay in the onset

Question 103

Puberty in females:

Answer 103

Growth of breast tissues, growth of axillary and pubic hair, growth spurt ~9-11, menarche (start of menstruation)

Question 104

Puberty in males:

Answer 104

Growth of testes, followed by growth and pigmentation of scrotum and growth of penis, growth of armpit, pubic, chest, and facial hair, testosterone stimulates growth of larynx and thickening/lengthening of vocal cords, ejaculation with sperm at ~15 years, growth spurt at ~11-13, development may occur through early 20s

Question 105

What is menopause?

Answer 105

Ovaries become less responsive to gonadotropin signals § Estrogen production declines § Ovarian cycles may release 0 to 2+ oocytes § Menstrual periods become erratic and shorter Menopause: § Ovulation and menstruation cease § Occurs between ages of 46 and 54 § Estrogen production eventually ceases

Question 106

What are the effects of a lack of estrogen?

Answer 106

Atrophy of reproductive organs and breasts, vaginal dryness, irritability and depression, vasodilation of skin’s blood vessels (hot flashes), loss of bone mass o May be treated by low doses of estrogen § Hormone replacement therapy (HRT), controversial: may increase risk of heart disease, breast cancer, stroke, and dementia

Question 107

Is there an equivalent to menopause in men?

Answer 107

No equivalent in men, but: § Testosterone production does decrease, refractory period after orgasm increases, sperm motility decreases § May be treated testosterone replacement therapy